Quick Question- What temps should a 94 Merc 305 Run at

Bry21317

Chief Petty Officer
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Apr 9, 2002
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552
I am just wondering, if anyone knows exactly what temp a 94 Merc 305 Should run? I have a 140 Thermostat in there, which is from the Dealer, just wondering what the correct running temp on that engine should be.

Thanks,
Bryan
 

Bt Doctur

Supreme Mariner
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Aug 29, 2004
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19,343
Re: Quick Question- What temps should a 94 Merc 305 Run at

that sounds like raw water cooled ,so it should hover between 140-145.
 

Bry21317

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Apr 9, 2002
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Re: Quick Question- What temps should a 94 Merc 305 Run at

Yes it is raw water cooled.

Thanks for the input.

Bryan
 

John_S

Rear Admiral
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Jun 21, 2004
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4,269
Re: Quick Question- What temps should a 94 Merc 305 Run at

You put a new thermostat in. What was it rated for, 140 or 160? The dash temp gauge will typically be 10-15 degrees higher than thermostat rating for normal raw water cooled operation. Mine has a 160. Once warmed up, it stays at 175.
 

Bry21317

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Apr 9, 2002
Messages
552
Re: Quick Question- What temps should a 94 Merc 305 Run at

I put in a 140, which is what it stated in the manual. I was just wondering what temp it should stay at. As I have not yet gotten the boat back from the mechanic, but he stated it was running just under 175 on the muffs after last night.

Before he had it, it never got over about 165-170. I will find out, when I get it back, what it does when I try it out.

Bryan
 

Mkos1980

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Oct 25, 2007
Messages
640
Re: Quick Question- What temps should a 94 Merc 305 Run at

i have the merc 140-142 stat and it stays dead on 140. Only time it rises is "after" a hard run . Even then it'll get up to 150-155 at most.
 
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